This invention relates to a device for the introduction of gaseous medium such as air into liquid such as drain water, the device being of the kind which withdraws a portion of the liquid to be aerated and discharges it under pressure through at least one nozzle element by which the liquid passes through a space filled with air of which part is entrained in an ejector nozzle through which these mixed portions of the liquid and air are returned into the fluid to be aerated.
There are known radiating aerators of this kind in which the liquid is passed under pressure into an inner chamber from which it is discharged through nozzle elements arranged spaced and angularly displaced in relation to one another into an outer chamber surrounding the inner chamber, the outer chamber being connected to an air supply conduit and having nozzle elements arranged to be complementary to the nozzle elements of the inner chamber, whereby the outer chamber nozzle elements receive the liquid jets from the inner chamber nozzle elements and return the liquid with entrained air into the bulk of the liquid to be aerated.
These so-called radiating aerators must, however, be supplied with both the air and the liquid through special pumps or compressors, which may be mounted within or externally of the bulk of the liquid and must be connected through appropriate connection conduits to the radiating aerators.
One object of the invention is to provide a simplified form of construction in which there are substantially avoided not only the connection conduits between the radiating aerator and the pump or compressor and the appertaining costs of mounting the same, but in which also there can be used the very convenient pumps or motor-pump assemblies which are known as submersible pumps or as submersible motor-pump assemblies comprising electric motors and pumps connected therewith, in order thereby to furnish very effective aerating devices in a simple manner.